The multiple suicide bombings in northern Iraq today became the most deadly atrocity since the fall of Saddam Hussein with over 250 dead.

The Kurdish Health Minister, Zayan Othman, said that at least that number of people are now known to have died and 350 were also injured in the synchronised detonation of four truck bombs. Many children are thought to be among the dead.

The attacks were aimed at the Yazidi community, an ancient pre-Islamic sect whose relations with surrounding Islamic communities have been deteriorating in recent months.

Through the day rescuers used their hands to dig through the ruined clay houses of Qahataniya, near Iraq's Syrian border, to find the dead. As expected, the overnight death toll of 175 rose as more remains were found among the densely-packed houses, which collapsed quickly under the force of the blasts.

US military helicopters helped evacuate survivors to Dahuk, a Kurdish city 60 miles away.

"We are still digging with our hands and shovels because we can’t use cranes because many of the houses were built of clay," said Dakhil Qassim, the mayor of the nearby town of Sinjar. "We are expecting to reach the final death toll tomorrow or day after tomorrow as we are getting only pieces of bodies."

Witnesses said at least one of the explosions was caused by a fuel tanker rigged with explosives, which demolished shops and houses.

"My friend and I were thrown high in the air. I still don’t know what happened to him," said Khadir Shamu, a 30-year-old Yazidi who was injured in the blasts.

If confirmed, the death toll will make the attacks, which have been blamed on al-Qaeda, the bloodiest since the US-led invasion in March 2003. Until last night, the worst single attack took place on November 23 last year, when 215 people were killed by mortar shells and car bombs in the Shia district of Sadr City in Baghdad.

"I gave blood. I saw many maimed people with no legs or hands," said Ghassan Salim, a 40-year-old Yazidi teacher who went to a hospital to donate blood. "Many of the wounded were left in the hospital garage or in the streets because the hospital is small."

In Baghdad, the US Ambassador, Ryan Crocker, and the top US commander, General David Petraeus, who is due to deliver a crucial report on the progress of the American mission in Iraq next month, issued a joint statement condemning the "barbaric attacks".

"This indiscriminate and heartless violence only strengthens our resolve to continue our mission against the terrorists who are plaguing the people of Iraq," they said.

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